Carnival celebration starts on January 6, the Twelfth Night (feast of Epiphany), and picks up speed until midnight on Mardi Gras, the day before Ash Wednesday. Ash Wednesday is always 46 days before Easter, and Fat Tuesday is always the day before Ash Wednesday. Easter can fall on any Sunday from March 23 to April 25, with the exact date to coincide with the first Sunday after the full moon following a spring equinox! There you have it! Voila!